If yuo look at images of U.S. Army uniforms in the Civil War era, the chevrons used to indicate the ranks of privates, corporals, and sergeants are clearly point-down, like the current British Army’s chevrons (but much wider and thinner).
But today’s U.S. chevrons are point up (except for some “specialist” ranks). So far as I can tell, this change happened sometime before the First World War.
Has anyone pinned it down more specifically? When exactly were the chevrons turned, and, more important, why?
Specialists don’t have chevrons; they used to have ‘rockers’ – like Staff Sergeants and above, only upside down – but since they got rid of all the Specialist ranks except for E4, there are no more upside-down rockers… The Navy has downward pointing chevrons, and the Air Force has downward pointing “stripes” but adds upward pointing chevrons for the higher enlisted ranks. The Army doesn’t have any downward pointing chevrons in any ranks at the moment.
Sorry I can’t be more useful answering the actual question. The chevrons got turned (and the rank got smaller) around 1902-1903, I think, and the Army was going through a lot of changes around that time. Maybe they just wanted to change the enlisted ranks to reflect all the other changes going on at that time?